For GBA = Gekido Advance Kintaro's Revenge, Mario vs. Donkey Kong, Metal Slug Advance, Repro of english translated Mother 3 v1.2, Star Wars episode 3 Revenge of the Sith,
TMNT, F-Zero Maximum Velocity, Mario Pinball Land.
For GB/C = Batman The Animated Series, Avenging Spirit, Donkey Kong, DuckTales, Bonk's Adventure/Revenge, Looney Tunes, Pokemon Trading Card Game, Survival Kids,
Tiny Toon Adventures 2 Montana's Movie Madness, Who Framed Roger Rabbit, Yu-Gi-Oh Dark Duel Stories.
I tried to stay away from main stream games for the most part since i figured you either already have them, or other people would recommend them. Also i don't know how much these cost so take that into consideration.